Why would the Secret Service, in particular, want to tell sarcasm apart from other speech? Think about who they are.

They want to be able to distinguish sarcastic political speech, from sincere political speech. Of course both are protected speech.

Now, they might have a benign purpose, but from the description in TFA it doesn't seem so. After all, the administration would look pretty foolish if they tried to harass or jail someone for being sarcastic.

Actually, what they could do would be to correlate English language postings with equivalent German language postings. As Germans are known world wide for their fun-loving sense of humor and sarcastic wits, the difference should yield accurate, non-snarky posts in English.